摘要
面向业务和台站实际,针对露点温度直接和间接计算经验公式的不确定性,结合地基微波辐射计LV2级数据特征,开展了露点温度估算方案适用性及应用讨论,旨在为预报员提供高时空分辨率的基础物理量露点温度来判识大气饱和程度,服务于强对流天气预报预警分析。研究表明:(1)相对湿度是主导露点温度直接和间接计算公式计算结果差异的敏感因子。地基微波辐射计露点温度估算方案可为相对湿度小于50%时,采用直接计算公式;相对湿度为50%~99%时,采用间接计算公式;相对湿度为100%(饱和)时,温度大于-48.75℃,采用间接计算公式,温度小于-48.75℃,采用直接计算公式。(2)地基微波辐射计估算的露点温度产品精度保持了温度产品的高相关性,较大程度上改善了系统偏差,但离散程度略有扩大。其中,相关系数由0.99变成0.98,降低了0.01;系统性偏差由-3.18℃变成-0.98℃,缩小了2.2℃;均方差由4.92℃变成5.26℃,扩大了0.34℃。(3)相较相对湿度,估算的露点差对高湿区(相对湿度大于70%以上)较为“敏感”,能很好地“勾勒”出云等水凝物内部水汽饱和状态及其特征结构,便于用户判断出饱和区、非饱和区及两者过渡区;与地基微波辐射计直接测量产品联合,可监测强对流天气发生前、中、后水凝物垂直结构特征及其演变,便于天气预报预警,其中预警提前量可达0.5~1.0 h,降水结束预报提前量接近10 min。
In view of the uncertainty of direct and indirect empirical formulas for dew point tempera-ture,this paper discusses the applicability of dew point temperature estimation scheme based on charac-teristics of ground-based microwave radiometer data and its preliminary application.The purpose is to pro-vide the basic physical dew point temperature with high spatial-temporal resolution for forecasters to deter-mine the degree of atmospheric saturation,and to serve severe convective weather warning.The results show that:(1)Relative humidity is the sensitive factor for the difference between the direct and indirect calculation formula of dew point temperature.The dew point temperature estimation scheme based on LV2 data of ground-based microwave radiometer can be as follows:when the relative humidity is less than 50%,the direct calculation formula is used;when the relative humidity is between 50%and 99%,the indirect calculation formula is used;when the relative humidity is 100%(saturation),the temperature is warmer(colder)than-48.75℃,the indirect(direct)calculation formula is used.(2)The precision of dew point temperature products estimated by ground-based microwave radiometer keeps high correlation of temperature products,improving the system deviation to a large extent,but the dispersion degree is slightly expanded.Among them,the correlation coefficient changes from 0.99 to 0.98,reduced by 0.01 slightly;the systematic deviation changes from-3.18℃to-0.98℃,reduced by 2.2℃;the mean deviation changes from 4.92℃to 5.26℃,increased by 0.34℃.(3)Compared to relative humidity,the estimated dew point difference is more“sensitive”to the high humidity area(the relative humidity is more than 70%),and can well“outline”the saturation state and characteristic structure of water vapor in clouds and other hydrometeors.This is helpful for users to visually see the saturated area,unsaturated area and the transition area between them.Combined with ground-based microwave radiometer measure-ment products,the dew point temperature estimation scheme can monitor the vertical structure character-istics of hydrometeors before,during and after the occurrence of severe convective weather,which is a good reference for making weather forecast and early warning.The lead time of early warning can reach 0.51.0 h,and that of the end of precipitation forecast can reach 10 min.
作者
刘俊
周红根
安克武
吴泓
丁仁惠
Liu Jun;Zhou Honggen;An Kewu;Wu Hong;Ding Renhui(Taizhou Meteorological Office of Jiangsu Province,Taizhou 225300,China;Key Laboratory of Transportation of Meteorology,CMA,Nanjing 210008,China;Jiangsu Meteorological Observation Center,Nanjing 210008,China;Xinjiang Meteorological Technology and Equipment Support Center,Urumqi 830002,China;Nanjing Joint Institute for Atmospheric Sciences,Nanjing 210008,China)
出处
《气象与环境科学》
2024年第2期103-111,共9页
Meteorological and Environmental Sciences
基金
国家自然科学基金气象联合基金(U2342216)
南京气象科技创新研究院北极阁开放研究基金(BJG202107)
江苏省气象局挂帅揭榜项目(KZ202304)。
关键词
微波辐射计
露点温度
估算方案
强对流天气
microwave radiometer
dew point temperature
estimation scheme
severe convective weather
